As a palladium-containing supported catalyst for producing an α,β-unsaturated carboxylic acid through liquid-phase oxidation of an olefin with molecular oxygen, there has been proposed in, for example, International Publication No. WO 2002/083,299 A1, a supported catalyst of palladium metal which is formed by reducing a palladium salt with a reducing agent. Further, in Japanese Patent Application Laid-Open No 2000-202,287, a palladium catalyst for hydrogen addition reaction manufactured by supporting a dinitrodiammine palladium solution on an alumina carrier followed by reduction is described.